fix: update capacity validation to default to 1 if empty in preflight checks

preflight.sh

@@ -165,8 +165,10 @@ check_runners_ini_format() {
       errors=$((errors + 1))
     fi
 
-    # capacity: positive integer >= 1
-    if [[ -n "$capacity" ]] && ! [[ "$capacity" =~ ^[1-9][0-9]*$ ]]; then
+    # capacity: positive integer >= 1 (defaults to 1 at runtime if empty)
+    if [[ -z "$capacity" ]]; then
+      log_warn "  → [$section] capacity is empty (will default to 1 at runtime)"
+    elif ! [[ "$capacity" =~ ^[1-9][0-9]*$ ]]; then
       log_error "  → [$section] capacity='$capacity' (must be positive integer >= 1)"
       errors=$((errors + 1))
     fi
@@ -250,7 +252,7 @@ REQUIRED_VARS=(
   GITEA_BACKUP_INTERNAL_URL BACKUP_STORAGE_PATH
   GITHUB_USERNAME GITHUB_TOKEN
   REPO_NAMES
-  RUNNER_DEFAULT_IMAGE RUNNER_DATA_BASE_PATH LOCAL_RUNNER_DATA_BASE_PATH
+  RUNNER_DEFAULT_IMAGE
   TLS_MODE CADDY_DOMAIN CADDY_DATA_PATH
 )